The quantitative and qualitative analysis of the craniofacial skeleton of mice lacking the IGF-I gene.

Insulin-like growth factors are mediators of growth hormone and are believed to also stimulate growth independently. Insulin-like growth factor I (IGF-I) null mutant mice exhibit a lower rate of skeletal growth compared with their wild-type (control) littermates. Although their general body dimensions seem proportionate, their heads appear shortened with a blunt nose compared with the controls.

Effect of evaporation and mixing technique on die spacer thickness: a preliminary study.

Statement Of Problem: Casting relief is required for proper seating of castings to allow for luting agent thickness. The application of die spacer to the die is the most common method of obtaining casting relief. Die spacer film thicknesses that are outside the ideal range of 25 to 40 microm can cause clinical problems.

Dimensional accuracy of castings produced with ringless and metal ring investment systems.

Statement Of Problem: The ringless casting procedure is in use in clinical dentistry, although there is no adequate scientific data to support its use.

Purpose: This study compared the vertical margin accuracy of lost wax castings produced with the conventional casting technique using a metal ring and a technique that uses a ringless system.

Material And Methods: From copings fabricated on a metal die, 30 castings were produced from a high palladium alloy for metal ceramic restorations (Argedent).

Theoretical cantilever lengths versus clinical variables in fifty-five clinical cases.

Statement Of Problem: Cantilever loading increases loads distributed to implants, potentially causing biomechanical complications. The implemented length is often less than what is considered to be optimal.

Purpose: This study investigated the effects of clinical variables on predicted cantilever lengths.

Comparison of numeric techniques in the analysis of cleft palate dental arch form change.

Objective: Quantitative descriptions of form (size and shape) changes are significant to the understanding of the development, treatment planning, and prognosis of patients born with cleft lip and palate. This study compared the results of traditional dental arch form change measurements, such as width, depth, perimeter, and area, with four numeric methods: finite element scaling analysis, macroelement method, Euclidean distance matrix analysis, and conventional least-squares and resistant-fit theta rho Procrustes analyses.

Design: Using tooth cusp landmarks on maxillary study casts, form change measurements of a male with complete bilateral cleft lip and palate at ages 2, 5, and 6 years were made comparing each age to the next older.

Form difference computations in restorative dentistry utilizing the macroelement method.

The comparison between the size and shape (form) of two structures or the analysis of one object under differing conditions is important in restorative dentistry. Despite rapid advances in digitizing technologies, form comparison is still mainly limited to scalar measurements. The objective of this study was to test the potential use of a newly developed tensorial morphometric difference technique, the macroelement method, in a model restrative system where the processing and materials properties are known duplication of a denture anchor in stone via polysulfide, addition silicone, and polyether impression materials.

Determination of cantilever length-anterior-posterior spread ratio assuming failure criteria to be the compromise of the prosthesis retaining screw-prosthesis joint.

The maximum cantilever length-anterior-posterior spread (CL-AP) ratio is often used as an indication of the ability to cantilever in completely implant-supported prostheses. The CL-AP ratios were determined assuming that failure occurs when the prosthesis retaining screw-prosthesis joint was compromised by either compressive (exceeding the pretorque value) or tensile (opening of the joint via plastic deformation) vertical forces using the Skalak model. Geometric arrangements of three, four, five, and six implants were analyzed.

Effects of titanium dioxide passive film crystal structure, thickness, and crystallinity on C3 adsorption.

The effects of titanium dioxide passive film crystal structure, thickness, and crystallinity on C3 adsorption from diluted human plasma were measured. Titanium dioxide surfaces created include (1) 70-nm anatase and rutile films comprising a mixture of amorphous and microcrystalline titanium dioxide, (2) 140-nm anatase and rutile films with greater crystallinity than the 70-nm films, (3) 70-nm aged anatase films with approximately the same crystallinity as that of the 140-nm anatase films, (4) sintered anatase and sintered rutile with no underlying metal, representing completely crystalline oxide films of infinite thickness, and (5) electropolished titanium. All combinations of experimental variables of surface type, exposure time, and plasma dilution were replicated four times.

Use of the boundary element method for biological morphometrics.

Tensorial morphometric assessments of form difference can aid in the understanding of the cause of the form difference by providing reference frame independent, anisotropic, non-homogenous descriptions. The majority of biological and prosthetic structures cannot be adequately analyzed by current methods due to the paucity of anatomical landmarks and methodological requirements of subdivision through the domain. Internal subdivisions can be eliminated with the boundary element method (BEM).

An evaluation of growth changes and treatment effects in Class II, Division 1 malocclusion with conventional roentgenographic cephalometry and finite element method analysis.

Conventional methods of roentgenographic cephalometry will yield differences in interpretation of growth or treatment changes depending on which methods of superimposition are used. The finite element method of analysis has been reported to have significant advantages since it does not require a reference frame to describe the changes that have taken place. This article describes the growth of a patient with a Class II, Division 1 malocclusion during approximately 2 years of orthodontic treatment with the use of conventional cephalometric growth and static analyses, as well as the finite element method.

A modified direct technique versus conventional direct placement of brackets: in vitro bond strength comparison.

Bond strength and failure location were evaluated in vitro for two methods of direct bracket bonding. Sixty human premolars were divided into two groups of 30 each. In group I the brackets were bonded with a two-paste adhesive by using the conventional direct method.

Anatomical macroelements in the study of craniofacial rat growth.

In order to avoid the arbitrary division of biological structures, rational polynomial interpolants are utilized to study growth. The major advantage of this method is the elimination of artificial internal element boundaries through anatomical structures. Since the boundary element methodology is employed in the finite element setting, other benefits, without additional computer coding, include the ability to use elements with any number of sides and reference frame invariance.

TEM immunogold staining of C3 from plasma onto titanium oxides.

Immunogold staining in conjunction with TEM was used to observe C3 adsorption from plasma in relation to the underlying titanium structure of thermal, anodic, and electropolished oxides. Heat treatments and oxide thickness were found to have no significant effect on the adsorption behavior of C3, while surface oxide type possibly has. Surface concentration of C3 was found to be time- and plasma concentration-dependent.